Marine biofouling on the hulls of ships has been a problem for centuries. More recently, as more undersea sensors and robotic systems have been utilized for extended periods of time, the control of biofouling has become more critical. Historically, anti-biofouling coatings utilized biocides that leach out from the coating over time to thereby prevent biofouling settlement by virtue of the biocides' toxicity to marine organisms. This method of control has had a number of problems associated therewith. First, the biofouling resistance of the coating decreases with time as the biocides are depleted by their leaching out. Furthermore, the toxic coatings increase the danger of toxic exposure to shipyard workers, create a hazardous waste disposal problem, and have a detrimental environmental impact on marine wildlife.
The use of some elastomer based coatings resist fouling by presenting a surface that is unsuitable for strong adhesion of the fouling organisms. While silicone coatings have an inherent non-stick nature, it has been possible to provide satisfactory adhesion between silicone coatings and relatively rigid substrates by the use of one or more intermediate primer layers to provide a bond between the substrate, such as a boat hull, and the silicone outer layer. The silicone elastomer that has traditionally been utilized in these systems is of the room temperature vulcanizing type, also known as condensation cured silicone elastomers.
The best prior art known to the Applicants include U.S. Pat. Nos. 2,986,474; 3,973,510; 3,987,537; 4,025,693; 4,072,769; 4,312,693; 4,844,986; 4,894,254; 5,449,553; 5,691,019; 6,101,973; 6,221,498; 6,348,237; 6,403,105; and, 6,570,821, and published U.S. patent applications Ser. Nos. 2001/0032568 and 2004/0017731. None of the prior art systems disclose a two-part, heat cured silicone elastomer that is applied to a flexible tubing material for providing anti-biofouling. Additionally, the known prior art does not disclose a method for applying a silicone elastomer anti-biofouling coating in a continuous automated process.